Bore evacuator with elastic action



Oct. 16, 1956 w. MARGULIS BORE EVACUATOR WITH ELASTIC ACTION 2 Shets-Sheet 1 Filed Oct. 9, 1953 :E'il:

' I INVENTOR.

M73151: Murgl'ulia H 7&2 41w HITTOENEYS Oct. 16, 1956 w. MARGULIS 2,756,661

BORE EVACUATOR WITH ELASTIC ACTION Filed Oct. 9, 1953 2 Sheets-Sheet 2 INVENTOR. Wu] flu Mur 1111's BY =f Sttes BORE EVACUATOR WITH ELASTIC ACTION Waldo Margulis, Albany, N. Y., assignor to the United States of America as represented by the Secretary of the Army The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to cannons and particularly to a device for evacuating residual powder gases and other light weight matter from the bore of a cannon to prevent them from entering the firing compartment of the motor carriage thereof.

There is generally provided for cannons which have the breech open into a confined firing compartment, a device for evacuating residual powder gases from the bore after the projectile leaves the tube and while the breech is being opened so that the noxious fumes produced by firing the cartridge will not enter the compartment to be injurious to the operators therein.

At the present time, the means provided to evacuate the bore include a cylindrical metallic can placed around the tube with a plurality of ports providing communication between the bore and the interior thereof. These ports are arranged to extend angularly forward from the interior of the can into the bore of the tube. Hence, when a round is fired and after the projectile has passed the ports, the high pressure gases produced by the explosion enter the can through the ports and are stored therein until the projectile has left the muzzle and the pressure in the bore is less than that in the can. At this time, the stored gases rush forwardly out of the ports into the bore, accelerating the gaseous mass in the front end thereof out of the muzzle to produce in the rearward por-' tion of the bore a low pressure region which, when the breechblock is opened, causes a forward rush of air from the firing compartment through the bore to evacuate the residual powder gases and particles.

With this device, evacuation is oftentimes imperfect because the exhaust of the gases from the can is extremely rapid and if the breechblock is not opened during that time, evacuation does not take place. Further, this type of bore evacuator requires close machining of the tube where the can is joined thereto so as to seal the high pressure gases in the can. Also, because of the extreme pressure of the gases received by the bore evacuator the walls thereof have to be of considerable thickness and thereby considerable weight is placed on the muzzle end of the tube, moving the cannons center of gravity forwardly. This is undesirable in tank installation as it makes it necessary to move the breech of the cannon rearwardly in the firing compartment where space is at a premium. In addition, due to the large size of the metal canister, it is not practicable to carry spare parts within the vehicle.

It is, therefore, an object of this invention to provide for cannons a bore evacuator having a prolonged period of evacuation.

It is another object of this invention to provide a bore evacuator device which is easily replaceable.

It is a further object of this invention to provide a bore evacuator device which requires little or no special machining of the cannons tube where joined thereto.

' atent It is a still further object of this invention to provide a bore evacuating device of light weight so as to place as little weight as possible on the forward end of the tube.

It is, furthermore, another object of this invention to provide a bore evacuating device which may be compressed to a small size so that spare parts may be carried within the confines of the vehicle.

It is the specific object of this invention to provide an elastic action bore evacuator which is light in weight, is easily replaceable and does not require special machining of the cannons tube where joined thereto.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a perspective view of a cannons tube with the elastic action bore evacuator of this invention mounted thereon;

Fig. 2 is an enlarged perspective view of the gas deflector ring;

Fig. 3 is an enlarged perspective view of the bore evacuator clamping band;

Fig. 4 is an enlarged cross-sectional view of the tube with the bore evacuator mounted thereon; and

Fig. 5 is a view similar to Fig. 4 but showing the tube at the moment the fired projectile has passed the gas port with the elastic action bore evacuator partially inflated.

Shown in the figures is a cannons tube 12 having a longitudinal bore 13 therethrough and a plurality of annularly aligned gas ports 14 which extend inwardly and forwardly from the exterior thereof to bore 13. Replaceably encircling tube 12 rearwardly of ports 14, may be a gas deflector ring 15 having a strap portion 16 engageable with tube 12 and a deflector portion 17 which extends outwardly and forwardly from strapportion 16 into the path of the gases passing through g'as ports 14 from bore 13. Provided on each end of strap portion. 16 is an outwardly extending lip portion 18 having a suitable hole therethrough to receive a screw means 20 by which deflector ring 15 is drawn together to be securely clamped to tube 12.

- Encircling tube 12, so as to enclose gas ports 14 and deflector ring 15, i's an elastic sleeve 21, fabricated from suchmaterial as natural or synthetic rubber, which is securely sealed at the ends to tube 12 by clamping bands 22. The ends of clamping bands 22 may extend outwardly to form end portions 23, which are provided with suitable aligned'bores which receive a screw means 25 for contracting bands 22 toseal the ends of elastic sleeve 21 to tube 12. The, inner sides of clamping bands 22 extend arcuately away from tube 12 to provide thereby a rolling surface to contact the elastic sleeve during inflation;

The bore evacuator of this invention operates on theprinciple hereinbefore stated, that is, pressurized gases, produced when a cartridge (not shown) is fired in tube 12, enter sleeve 21 through ports 14 when projectile 26 has passed thereby and are exhausted therefrom after projectile 26 leaves tube 12. As ports 14 communicate with bore 13 at a forwardly inclined angle, the exhaust of the gases therefrom causes the gaseous mass in the front end of bore 13 to be accelerated out of the muzzle thereof.

This acceleration of the forward mass produces, rearwardly of ports 14, a low pressure region which, when the breechblock (not shown) is opened, causes a rush of air from the firing compartment to pass through tube 12, evacuating the gases and residue particles therefrom. Deflector ring 15 is provided to prevent the high pressure gases entering sleeve 21 from impinging directly against the wall thereof which might cause it to be damaged.

The use of deflector ring is limited to the cases where the material used for elastic sleeve 21 is susceptible to damage by direct gas impingement.

It is obvious, that by the gas container being elastic a greater volume of gases may be stored at a lower pressure than by the conventional can type evacuator of fixed volume. Consequently, the period of exhaust is increased to provide a more efficient evacuation. In addition, due to the elastic action of the container, the gases are delivered from the bore evacuator at a more nearly uniform pressure than is obtained from the metal can, thereby establishing a steady flow condition which is conducive to good evacuation. Moreover, the simply formed elastic sleeve 21 is cheaper to manufacture, and because of the nature of the material the problem of sealing the bore evacuator to the cannons tube, to prevent the loss of gases, is considerably reduced and eliminates the necessity for the close machining of the cannons tube Where sleeve 21 is joined thereto. Further, the elastic type bore evacuator of this invention represents an appreciable reduction in weight and inasmuch as the bore evacuator is normally located near the muzzle of the tube the reduction in weight represents a considerable breechward shift of the center of gravity which is desirable in cannon mount designs. Also, sleeve 21 is replaceable and spares may easily be carried, as they occupy very little space as compared with the can type evacuator.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. A device for evacuating from the bore of a firearm tube residual gases produced by the firing of a cartridge therein, comprising an elastic storage compartment sealed to the outside of the tube, there being a plurality of gas ports formed in the wall of said tube for bleeding pressurized gases from the bore to said storage compartment, said ports inclined towards the muzzle end of said tube for permitting said pressurized gases to be returned to the bore by the elastic action of said compartment and producing a low pressure region in the bore whereby air is drawn forwardly therethrough for evacuation of the residual gases therein. 7

2. For a firearm having a tube with a longitudinal bore therethrough, a device for evacuating from the bore residual gases produced by the firing of a cartridge therein, comprising an elastic gas tight sleeve to surround the tube, clamping'means for sealing the ends of said sleeve to the tube, there being a plurality of gas ports formed in the wall of said tube and being inclined towards the muzzle end thereof for bleeding pressurized gases from the bore into said sleeve for pressurized storage therein, said gas ports permitting said pressurized gases to be returned to the bore by the elastic action of said sleeve and produce a low pressure region in the bore whereby air is drawn forwardly therethrough for evacuation of th residual gases therein. r

returned by contraction thereof to the bore, and means.

for deflecting the gases entering said sleeve so as not to impinge directly on the wall thereof.

4. A device for aspirating residual gases from the muzzle end of a gun barrel having a bore and comprising, an elastic sleeve concentric about a forward portion of. said barrel, annular means encircling theends of said sleeve and providing a pressuretight fit between said ends and the gun barrel, said sleeve being distortable by gas' pressure engendered by a cartridge fired in said barrel to form a gas entrapping chamber, there being a plurality of gas ports formed in the wall of said barrel and inclined toward the muzzle end thereof, said gas ports providing communication between the said bore and said gas chamber, and to release entrapped air from said chamber into said bore to induce fluid flow in a forward axial direction upon a drop in pressure in said bore.

5. A device for evacuating from the bore of a fire arm barrel residual gases produced by the firing of a cartridge therein, and comprising an elastic sleeve sealed to the outer surface of said barrel and forming an expandable gas storage compartment, there being a plurality of circumferentially aligned ports extending through the wall of said barrel and inclined toward the muzzle end thereof,

7 said ports providing communication between said bore bore, a device for evacuating residual gases producedv by the firing of a cartridge therein and comprising, an

elongated elastic sleeve surrounding a forward portion.

of said barrel and having its ends secured in gas tight engagement about said barrel to form a chamber for entrapping gases, therebeing a plurality of circumferentially aligned gas ports extending through the wall of said barrel and intermediate the ends of said sleeve, said ports being inclined toward the muzzle end of said barrel,

and a deflecting ring encircling said barrel rearwardly of said gas ports, said ring comprising a forwardly opening flared out portion adjacent the outer ends of said ports.

References Cited in the file of this patent UNITED STATES PATENTS 515,064 Unge Feb. 20, 1894 FOREIGN PATENTS 585,851 Germany Oct. 11, 1933 531,143 Great Britain Dec. 30, 1940 221,036 Switzerland Aug. 1, 1942 628,774 Great Britain Sept. 5, 1949 

